Report memory retained by memory allocator internals.

webkit/glue/webkitplatformsupport_impl.cc

Index: webkit/glue/webkitplatformsupport_impl.cc
diff --git a/webkit/glue/webkitplatformsupport_impl.cc b/webkit/glue/webkitplatformsupport_impl.cc
index f0659d2d1b7ea22fd8f1a1adf8291f0ca298c43c..4f223330bf5000214e3cbc95b4ad68f4cb34a21b 100644
--- a/webkit/glue/webkitplatformsupport_impl.cc
+++ b/webkit/glue/webkitplatformsupport_impl.cc
@@ -12,6 +12,7 @@
 
 #include <vector>
 
+#include "base/allocator/allocator_extension.h"
 #include "base/bind.h"
 #include "base/debug/trace_event.h"
 #include "base/memory/scoped_ptr.h"
@@ -796,6 +797,19 @@ bool WebKitPlatformSupportImpl::processMemorySizesInBytes(
   return CurrentProcessMetrics()->GetMemoryBytes(private_bytes, shared_bytes);
 }
 
+bool WebKitPlatformSupportImpl::memoryAllocatorInternalsInBytes(size_t* size) {
+  size_t heap_size, allocated_bytes, unmapped_bytes;
+  if (base::allocator::GetProperty("generic.heap_size", &heap_size) &&

[darin (slow to review), 2012/10/18 18:02:54]

nit: Shouldn't there be some named constants for these strings?  It seems
fragile to hard-code these string literals here.

Alternatively, would it make sense for base::allocator:: to declare a method
that corresponds to memoryAllocatorInternalsInBytes?

One more note: I find the name memoryAllocatorInternalsInBytes to be quite
mysterious?  What does it mean?  Is it trying to count the number of bytes that
get used up by the allocator's own data structures?

[alph-g, 2012/10/22 12:19:41]

Hmm, I don't see any significant benefits of a generic
base::allocator::GetPropery with a string selector over the dedicated function.
I think it is possible to go with your suggestion. If we ever need another
function we can consider other options or return back to GetProperty way. I'll
implement the version you suggested.
Initially it was Waste instead of Internals, but James didn't like it. I took
the word Waste from the tcmalloc DumpStats report which btw also appears on the
chrome://tcmalloc/ page.

+      base::allocator::GetProperty("generic.current_allocated_bytes",
+                                   &allocated_bytes) &&
+      base::allocator::GetProperty("tcmalloc.pageheap_unmapped_bytes",
+                                   &unmapped_bytes)) {
+    *size = heap_size - allocated_bytes - unmapped_bytes;
+    return true;
+  }
+  return false;
+}
+
 void WebKitPlatformSupportImpl::SuspendSharedTimer() {
   ++shared_timer_suspended_;
 }